1. Field of the Invention
The invention relates to a driving device, more particularly to a light emitting diode (LED) driving device for driving an LED module.
2. Description of the Related Art
Conventional dimming techniques for adjusting illumination of a light emitting diode (LED) can be classified into two categories, specifically, analog dimming and pulse width modulation (PWM) dimming. Analog dimming for an LED is accomplished by adjusting amount of current flowing through the LED. However, color temperature of light emitted by the LED varies as the amount of current is adjusted.
On the other hand, in PWM dimming, an amount of current flowing through an LED is constant, and the LED is turned on and then, is turned off in a short period of time. Namely, PWM dimming is to adjust duty cycle of the LED, and the illumination of the LED depends on the duty cycle of the LED. Additionally, switching frequency of the LED should be high enough (e.g., more than 100 Hz) to avoid a human-sensible flicker effect.